PHP 静态关键字static
<?php class glass{ public $name; public $height; public $weight; public $color; public static $capacity;//定义静态变量capacity 容量 function __construct($name,$height,$weight,$color,$capacity) // 问题1:构造函数前面是function,不是public { $this->name=$name; $this->height=$height; $this->weight=$weight; $this->color=$color; self::$capacity=$capacity; echo $this->name."杯子的高度为"."$height"."\n"."$this->name"."杯子的颜色为"."$color"."\n"."$this->name"."杯子的容量为"."$capacity"."\n"."\n"; } function __destruct(){ echo "销毁".$this->name."杯子"."\n"; } public static function ChangeCapacity($newcapacity){ self::$capacity=$newcapacity; // echo "$this->name"."$newcapacity"."\n"; } } $glass1=new glass("num1","500mm","100mm","蓝色","500ml"); // $glass2=new glass("num2","300mm","500mm","黑色","750ml"); // $glass1->ChangeCapacity("900ml"); //问题2:修改静态成员参数值的方法 // 应使用 类名::成员参数("参数值"); //输出 echo 类名::$成员参数; glass::ChangeCapacity("123"); echo glass::$capacity."\n"; $glass3=new glass("num3","100mm","100mm","白色","520ml"); ?>
在下面修改了glass类中capacity参数为123,但是后面再次实例化对象后,输出的$capacity值仍为定义的"520ml",而不是修改后的值:123